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| From the Canadian Series "Murdoch Mysteries" |
Firearms account for 32% and 60% of homicides in Canada and
the United States respectively.
Gunshot wounds are separated into different categories based
on range and type of weapon (caliber of bullet etc.)
·
Contact
wounds appear when the gun is pressed against the skin when fired. A black,
round wound will appear on loose skin (chest, abdomen) and may appear in areas where the skin is tighter against the skeleton
like the head but bruises and stellate-shaped wounds can also appear. Soot
often appears on contact wounds along with muzzle imprints and lacerations of
the skin from the effects of gases.
·
Near
contact is when the gun is held a short distance away from the skin. The
wound that appears is black and circular.
·
Intermediate
can appear from a variety of ranges but is marked by the stippling that appears
around the entry wound caused by unburned powder causing pinpoint abrasions on
the skin.
·
Distant
also produces stippling and also round wounds with an abrasion ring on the
surrounding skin. They will typically produce a hole roughly the caliber of the
projectile fired.
·
In contact wounds to the head with center fire rifles, there is massive
tissue damage to the skin, skull, and brain. Full metal jacketed bullets have
less tissue damage and usually travel through the body undamaged. In
half-jacketed bullets the jacket peels back as it travels through the body
releasing several small lead fragments.
·
Shotgun shellscontain
numerous pellets. At close range the entry wound is singular and round but as
the range increases the central wound becomes smaller and the number of
surrounding pellet holes becomes larger. The further away the weapon is when
fired, the wider the spread of pellets, causing multiple entry wounds.
·
In flat bones like the skull, entry wounds are
round and show internal beveling in which the inner table of the skull is more
eroded than the outer producing a cone shape in the bullet’s path, sometimes
carrying fragments of bone with it. Numerous fractures may also appear on the
skull due to rapidly increasing pressure as the bullet travels through the
skull. Bevelling can be used to determine the direction of the bullet passing
through bone.
·
Shoring
occurs in an entry wound when the bullet passes through a firm object before
breaking the skin such as wood, glass, metal. Shoring produces as a greater
wound diameter and greater marginal abrasions.
Exit wounds usually create an irregular shape and don’t show
the same signs as entry wounds: muzzle imprints, stippling, black bruising,
etc. They are typically larger than the entry wound and can also be numerous
due to fragmentation. Entry wounds do not occur during every shooting. The
bullet or projectile may remain inside the body or object that it hits.
Gun powder residue is a good way to distinguish between a
Contact and a Distant wound through many factors:
1.
Firing distance
2.
Length and diameter of the firearm barrel
3.
Angle between the firearm barrel and the target
4.
Characteristics of the cartridge
5.
Environment (wind, rain, heat)
6.
Type of clothing
7.
Intermediate targets
Different types of guns use different calibres of bullet or
even different types of projectiles eg shells.
These will leave different marks. Admittedly I know very little to absolutely
nothing about guns so I’ll just leave this link here for you to read:
You can read the rest of the Forensic Friday series here:
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